Search

Abstract: The aim of this experiment was to study the effect of the application of pig slurry on potential pathogen (total and faecal coliform bacteria) presence in a Typic Xerofluvent soil. The experiment was conducted in field conditions, in the Segura River valley in the South East of Spain. Four treatments, in a fully-randomised design with three replicates per treatment, were established in experimental plots of 16 m2 each. Fertiliser treatments were: MF, mineral fertiliser (with a complex 16N–16P2O5–16K2O) equivalent to 150 kg N ha−1; PSF, organic fertilisation with swine manure slurry, at two different rates (supplying 150 and 210 kg N ha−1), and C, a controlled treatment without fertilisation. A high variability of the concentrations of total and faecal coliforms was observed during the experiment, mainly depends on the time and the treatment. The pig slurry amendment induced the highest initial and also persistent presence of total and faecal coliform bacteria. The higher application rate seemed to induce a long-lasting persistence of the total, but especially the faecal coliform, population in the amended soils compared to the lower rate. In most cases, an increase in the total coliforms content was observed in the soils amended with mineral fertiliser compared to controlled soils, probably due to an increase in soil microorganisms populations. In general, the total coliform bacteria was 2–3 log10 units higher than the faecal ones. Mostly, a tendency to decrease with time was observed in both indicator microorganisms, in all the treatments. [Copyright &y& Elsevier]

Abstract: The contents of available nutrients in pig slurries are not easy to quantify in situ without laboratory facilities, but chemical analyses using standard laboratory methods also take time and are costly and not practical for most farms. Thus, when animal slurries are applied to land, their fertiliser potential is often unknown. In addition, in the last years, the changes in the management of industrial piggeries has changed the nature of the pig slurries vg. decrease of the dry matter content, and consequently the methods and equations used for estimating the nutrient contents in these residues must be checked. In our study, slurry samples were collected from the storage tanks of 36 commercial farms in Southeast Spain. Samples were analysed for pH, electrical conductivity (EC), redox potential (RP), specific density (D), total solids (TS), sedimentable solids (SS), biological oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (TKN), ammonium nitrogen (AN), organic nitrogen (ON), and total contents of phosphorus, potassium, calcium and magnesium. Relationships between major nutrient levels of pig slurries and a range of physical and chemical properties were investigated. We also analysed the variability of pig slurries according to the production stage. TKN, AN and K were closely related to EC. The P content in slurries was related more closely to solids-derived parameters such as D. The use of multiple properties to estimate nutrient contents in pig slurries, especially for AN and K, seemed unnecessary due to the limited improvement achieved with an additional property. Therefore, electrical conductivity seemed to be the most appropriate single, easily determined parameter for estimation of total and ammonium nitrogen and potassium in pig slurries, with more than 83% of the variance explained. P seemed to be the worst key nutrient for estimation using any easily determined parameter. [Copyright &y& Elsevier]